I'm wired up and coated in sensors. Guinea pig 16 in a research of how warmth impacts the human physique.

It's 50C within the heated "climate chamber" on the University of Roehampton in west London. The air instantly catches in my throat, my pores and skin prickles.

And that is solely marginally above the European temperature report of 48.8C.

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For an hour I've to lie nonetheless whereas scientists observe my physiological response.

My coronary heart fee rises steadily from 57 to 79 beats a minute.

It's pumping more durable to compensate for a drop in my blood stress.

Chris Wolf is the scientist working the research. He tells me my physique is attempting to shed warmth by opening up blood vessels in my pores and skin.

"This is all linked to trying to keep yourself cool," he stated.

"If you've ever looked down on that hot day and seen that hot, flushed skin, that's our blood vessels dilating or widening.

"The physique's attempting to extend blood movement to the floor of the pores and skin and enhance the quantity of warmth we are able to lose."

So far so good. I'm not sweating too much and the rectal probe monitoring the temperature deep inside my body shows only a small rise.

But then I jump on an exercise bike to simulate activity in a heatwave.

The tempo is regular, nothing extraordinary. But my coronary heart fee rapidly hits 170 and thousands and thousands of sweat glands attempt to cool me down.

It does not work. My physique temperature soars greater than 1.5C, passing 38.6C after 20 minutes on the bike.

That's the type of temperature you attain with a excessive fever.

And it retains climbing, even after I escape the warmth of the chamber.

Even for wholesome individuals, exercise in excessive temperatures will be harmful.

A street employee in Italy is believed to have died on account of the present heatwave.

But typically warmth is a silent killer. It's solely weeks later when statisticians look again that they see a steep rise in extra deaths - greater than 61,000 of them in Europe final summer time.

Some of these are individuals with heart problems, unable to deal with the extra pressure on their hearts.

But older individuals make up a lot of the deaths. Their our bodies do not reply rapidly sufficient to warmth and so they cannot hold cool.

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Professor Lewis Halsey, an environmental physiologist on the University, defined what truly occurs because the physique's temperature builds.

"Proteins start to fall apart and stop working so well, nerve impulses through the body don't work so well, and biochemical reactions become sub-optimal.

"So the organs within the physique operate much less nicely.

"And if that happens too much it can be fatal."

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I'm not within the hazard zone, however I used to be solely uncovered to excessive temperatures for a few hours.

People in southern Europe and the US have been dwelling it for days.

And their our bodies shall be severely examined.